Machines used in the farming, construction, mining, power generation, and other like industries commonly include a frame that supports an internal combustion engine, a work tool movably connected to the frame, and at least one hydraulic cylinder connected between the frame and the work tool and driven by the engine. Such machines typically operate in harsh environments characterized by large amounts of airborne dust, dirt, and debris. In such environments, it is desirable to remove such debris from the air before directing the air to the engine. To assist with this process, such machines typically include an intake air filter or other like air cleaner configured to remove airborne debris upstream of the engine. Further, to assist in prolonging the useful life of such air cleaners, some machines may also include a pre-cleaner configured to remove relatively large debris from the intake air stream prior to cleaning the intake air with the air cleaner.
An exemplary air intake system employing a pre-cleaner is disclosed in U.S. Pat. No. 8,177,872 (“the '872 patent”), issued May 15, 2012. The pre-cleaner taught in the '872 patent includes a plurality of inertial separators disposed within a housing that is fluidly connected upstream of an engine air cleaner. As intake air is drawn into the housing, the inertial separators remove relatively large debris particles from the air and deposit them within the housing. These particles are then removed from the housing via a scavenge pipe fluidly connected to the exhaust system of the engine.
While the system of the '872 patent may be configured to remove relatively large debris particles from intake air, such systems are known to have several drawbacks. For example, in relatively high-debris environments, the inertial separators used in such systems are easily clogged. Once clogged, such separators can be difficult to clean due to their size, location, and configuration. Additionally, as such separators become clogged, air flow through the pre-cleaner is reduced. If left unchecked, this reduction in air flow can create an area of low pressure within the pre-cleaner strong enough to draw high temperature exhaust into the pre-cleaner. Such high temperature exhaust can damage the pre-cleaner and can have unwanted effects on the combustion process within the engine.
Moreover, scavenge pipes of the type disclosed in the '872 patent often have difficulty removing debris that has been collected within the pre-cleaner housing. Since the vacuum flow through such scavenge pipes is typically dictated by engine speed, the debris removal capabilities of such scavenge pipes can be significantly reduced at engine idle or other modes of engine operation characterized by relatively low engine speed. As a result, collected debris can accumulate within the housing over time. Due to the number and close proximity of inertial separators employed by such pre-cleaners, operators may have difficulty manually removing such accumulated debris from the pre-cleaner housing, and this built-up debris can reduce the efficiency of the pre-cleaner.
Accordingly, there is a need for improved pre-cleaner systems to address the problems described above and/or problems posed by other conventional approaches.